Luminous tube sign



May 10, 1938. A. c. DEANS LUMINOUS TUBE SIGN Filed Aug. 51, 1956 3 Sheets-Sheet 1 IN VENTOR M $1M May 10, 1938. c, DEANS LUMINOUS TUBE SIGN Filed Aug. 31, 1936 3 Sheets-Sheet 2 INVENTOR May 10, 1938. A. DEANS 2,116,721

LUMINOUS TUBE 5 IGN Filed Aug. 51, 1936 3 Sheets-Sheet 3 fawn-awn. I N VEN TOR Patented May 10, 1938 UNITED STATES PATENT OFFICE LUMINOUS TUBE SIGN Arthur Clitton fieans, Los Angeles, Calif. Application August 31, 19st, SerialNo. 98,685 9 Claims. (01. 41 m) the letter strokesbehind the 'tubes are often of light color. It is well known that readability decreases with the increase of the letter stroke.

1 It is an object of this invention to reflect the light which would ordinarily be sent ontothe background by means of a mirror surface onthe back side of the tube itself. Thus, the light source presented to the eye is no wider than the tube itself, thereby increasing the readability. One should also bear in mind thata mirror-surface on glass has a high luminous efficiency which does not change with time, whereas a paint surface on metal has a low luminous efiiciencyand falls off rapidly with the aging of the paint and the accumulation of dirt. 1

The advantages of this device are many. The

entire angle of rays which are not sent directly forward from the glowing gas is thus conserved. With the prior art, even with the widest letter stroke permissible, only a fraction of the light sent backward is caught. Often this fraction is no more than one third, and rarely isit over one half of the backward light. 1

Another common practice of the prior art involves the construction of channels around the tubes to conserve the light. With signs made according to this invention the practice of providing channels or troughs for the tubes may be dispensed with entirely. The sign characters may be painted on the body of the sign proper or they may be raised slightly asshown in the drawings.

'I'he invention is equally adaptable to'skeleton viding a tube in the form of an extra w'ordor ornamentation projecting above, below or to the side of a regular type of sign. The reflector on the tube obscures the light in the reverse direction and the efficiency in the proper direction is every bit as high as though the tube were made to appear on a background. Various other adaptations of the invention will be apparent to those skilled in the art, all within the purview of the claims. 1 9

Another object of the invention is'to provide means to prevent electrical breakdown between critical points of a configuratedtube provided 5 with a metallic reflective coating. 1 Such critical points are found where points spaced along. thelength of the tube approach each other at cross overs. return bends, parallel bends,f .etc. It has generally been believed that the breakdown tend- 10 ency wasmore orless a direct function of the stress imposed on the glass by the proportionate voltage drop between such points as regards the total voltage drop between the terminals of the tube. I have found that the breakdown tendency 15 develops in a very diiferent manner than this theory would indicate and apparently follows some law as yet unexplained. This, tendency is' materially in excess of what was expected with tubes with a continuous coating along convoluted 20 portions. However, in accordance, with my invention, tubes of the character described may be manufactured and installed with the same facility as ordinary tubes and will operate entirely satis factorily under all conditions. 1 1 25 Other objects of the invention will become apparent as the description proceeds. Since the invention may be variously modified within the broad principles herein disclosed it, is'my intention that it be not limited to the particular em- 30 bodiments herein disclosed but be interpreted to cover all modifications and embodiments within the broadest language of the claims.

The preferred form of the invention is shown in Figures 1 and 2 in which a sign is shown with 35 raisedtype letters and with a tube provided with a reflective coating positioned a short distance in front of the letters. I 1

FigureB is a cross section, very much enlarged, of a tube provided with a reflective coating and a protective coating over it.

1 Figure 4 isan enlarged view in perspective of the upper part of the letter ,t to show the manner of providing the coating. It is taken at the same angle of view as that of Figure 2. 45

Figure 5 is an enlarged view of the letter e taken at the same angle of View as that of Figure 2.

Figures 6, 7, 8, 9 and 10 are sectional views taken as indicated by the sections lines 6-6, 'l--1, 8-8, 9-9 and Ill-l0, respectively, inFigure 1. In these views the coatingsare greatly exaggerated in thickness for purposes of illustration.

The same numeral is used throughout all of f the views to indicate the same part or element.

Numeral I indicatesa sign body on which is constructed the raised character form indicated by 3, 3, etc. The character outline is in representation of the word Rite in script. The luminous'tube, indicated by 2, follows the form of the 7 character and is positioned a short distance from the character faces by means of the insulating posts 8. 8, etc. The ends of the tube are formed as electrode terminals, 6 and I, which extend backward into the ter'ininalhousings, 4 and 5. Within the sign, but not showir on the drawings,

are the usual transformer and high tension contions which properly represents the corresponding character element. The principles of the instant invention apply equally well in either case. Portions of the tube not representative'of the inscription proper are obscured by opaque paint as the section indicated by 9.

In the views the returnbends are indicated by 40., l2, l3, l4, i5-ahd Hi. When the bends are formed in this manner'it is permissible either to obscure the rearward portion of vthe bend by means of opaque paint or to leave it clear. Ac-

cording to my invention the reflective surface may be placed on the forward portion and the rearward portion obscured, or the reflective surface may be placed on the rearward portion and the forward portion left clear. I prefer however to use the first method inasmuch as it produces a much more clear cut effect.

' It also happens very frequently in the forming of characters that the tube makes a loop and approaches itself to complete the representation of a looped element in the character. It isnecessary in all cases that there be some space left at the approaches. Numeral 20 indicates such a condition at the end of the return bend ll. At this point there exists an electric stress equal to the drop in voltage through the looped portion of the tube. The separation, if too great, will spoil the appearance of the sign. If-

the glass.

The thirdcondition is that ofcross overs as indicated at l9. Here also the matter of separation is important because of the distortion of the character at an angular view if theseparation is too great. It is usual in the best practice to loop one part of the tube back of the other to retain the major portion of the tube in a single plane at such places.- v

It will also be noticed in connection with the letter Rf"that as the tube branches ofi at I I at the end of the return bend II it is formed to rise to the forward plane of tube contour too small, it leads to electric breakdown through as indicated by l6. This also conforms to the best practice in tube bending. There are thus numerous places where a potential exists between adjacent points on the tube. While it might be thoughtthat the im-' portance of such conditions would be determined by the potential drop down the tube between the two points in each case, I havefound that other factors are at play making the conditions at such What these factors may be remains'a matter of conjecture.

My theory, however. is that high frequency action takes place within the tube between such points; When a conductive coating is placed on thetube this action gives rise to discharges into the air between the adjacent points It is these free discharges into or through the air which disintegrate the glass at such points resulting finally in breakdown through the glass.

Whether this theory be correct or not is not to be considered as controlling the importance of this disclosure, for it is well known that the effects within gaseous conduction tubes are still subjects of scientific debate.

By following the instructions below it is possible to produce tubes with conductive and reflective coatings which will give as good service as the conventional uncoated tubes. It is to be ure 4 by broken lines. The ends of the various are all terminated a short distance back from sections of the coating near the junction point 34,. I

the junction. This distance is a matter of empirical determination because of the many variablesin this work. The opposite ends of the coating 3!, 32 and 33 terminate at the ends of the respective arms of the letter t and hence do not continue on the under portions of the return bends. The reflective coating is covered by a non-conductive coating of paint or lacquer which is indicated by 34, 35, 36 and 31. This protective coating may well be continued aroundthe tube, covering up the under portions of the return bends as indicated at 33, 39 and 40. In Figure 4 the protective coating is indicated by the full parallel shading lines.

Referring now to Figure 3, I show the preferred manner of coating the tube. The tube is indicated by 4| and the. reflective coating by 42. This coating may be formed from any of-the metallic substanceswhich have been used for this purpose. I prefer however, the use of aluminum deposited in vacuunn It is preferable to protect the metal by the coating 43 which extends a short distance over the edges of the metal as indicated ,at 44 and 45. If the protective coating is of light color it assists the reflection at such places. It is usually best to construct this reflector to extend about one half way around the tube.

Again referring to Figure 4; it -will be noticed that there are various places where the character outline is not followed by 'the reflector. Such places are indicated by 48, 41, 48, 43 and 50. By making the protective coating of light color, however, this is partially overcome. I have found, as a matter of fact that, so'far as the observer is concerned, such discontinuities become of no consequence. This is due to the fact that the discontinuities fall at the places where the optical effect is enhanced by the approaching tubes. The use of light colored paint thus is suilicient to give an effect continuous to the eye.

With this as typical of the return bend practice, we now referto Figure 5 and the sectional views in Figures 9 and 10 where I show enlarged q the letter "e. Here, the reflective coating isindicated by 52 and 53, being shown in Figure 5 by broken lines. 'Theprotective coating is indicated by 54 and in Figure 5 is shown by the junction.

full parallel shading lines. We observe that there are two discontinuities in the reflective coating, indicated by 55 and 56. It is permissible in some cases to have a discontinuity at but one place,

although the best practice is as shown in the drawings. Here also we have the condition of the optical illusion helping out theefl'ect'of a continuous line of light of uniform intensity when light colored protective coatingis provided. This maybe taken as typical of cross overs.

In Figure 6 I show thetreatment for approaches as, at, 20. The vertical; stroke of the tube is indicated by 51 and the return bend by H.

Here the reflective coating, indicated by 58 ter-a minates at 591a, short distance back of the i The protective coating fills out the character at 60 and completely. covers the tube at 61 onthe under portion of the returnibend.

The protective coating on the sectioni'l is, indicated by 10, the reflective coating having been removed from this region. i i 1 Referring now to Figure 2, it is to be noted indicate the coating on the tube, but the position of the ends will be apparent from the above.

The arrangement shown in Figure 3.; have found to be themost satisfactory for the construction of the mirror. It willbe noted. that the reflective coating isjust a little short of semicircular and that the protective coating passes over the edge a'short distance to protect the edges from corona discharges. The protective coating, if of light color assists the reflectionqat such places as it contacts theglass direct. Dark colored paint, naturally, may be used if desired.

However, in cases wherea dark obscuring paint is desired, I flnd it better to apply a light paint .first and cover it with dark paint. In installations where the potentialis not very high it is not necessary to cover the edges of the coating.

As the most serious cause of breakdown arises at such places as the double backs, the ap-- proaches and the cross overs, most careful attention should be given to such places.

potential drop might be very small. For some reason, not yet discovered, the potential drop is not the important factor as compared with the otherjconsiderations pointed out, above. Coating on parallel sections of tubing should in particular be avoided. At all places where the tubing approaches grounded metal the coating should be eliminated. Such places are found at the electrode terminals.

The most satisfactory material for the reflector is aluminum vaporized and deposited in vacuum.

' Other' materials may be used, however, within the purview of this invention. i

In designing signs with tube made according to my method, the designer should bear in mind that the elimination of refle'ction from the backclaim is: i

that at the ends of theltube at. the'points indicated byit2 and .63 terminations of thecoating arealso to be made. The view is too line. to

One should not be misguided here by the fact that the actual,

This is naturally, an illusion. The. effect tends to pullinto the corners and detract from the character. .In thecase of tubes which develop a wormyeflect, the reflector also tends to improve the appearance by filling out the tube withlight to the, eye so that the swirling gas column is not noticed. The term ,.character "as used in the claims is tobe understood as including any configuration of the tube in representation ofletters, numerals;

borders, symbols, ornaments or designsor the like. i

The term "light colored" is to be understood as including white." 1. i

Theterm loop? is to be understood as defin-i ing any configuration of. the tube in which it follows a course from a given point through a portion of a. character and returns to or near the said point.

Having thus 5 1. A luminous tubein the form oi'a character having a portion which crosses over itselLa redescribed my invention, what I fiective coating of metallic nature on said tube er. said coating being formed with adiscontinuity, on at least one of the portions of saidtubelat the crossing point whereby to increase the air spacedistance between .the approaching portionsof saidcoating, and a reflective coating of non-conductive nature on said tube'extending across the said discontinuity to provide'a continuous reflective. coating on said tube corresponding tosaidicharacter.

2. A luminous tube in the form of a character having at least one portion formed to represent a branching character stroke, a reflective coating of metallic nature on said tube on the side thereof opposite the normal direction of the observer,

said coating beingtermlnated a distance from the junction thus, formed ,onat least one of its ,arms at said junction, saiddistancebeing sufficiently largeto substantially. prevent deleterious discharges at said junction and a coating of light colored non-conductive material covering the discontinuity in the reflective surface thus provided.

3. A luminous tube in the form of. a character, said tube forming a loop over a part of the course thus traced and returning toward itself without actually touching, a reflective coating of metallic nature on said tube on the side thereof opposite the normal direction of the observer,

said coating terminating a short distance from.

the junction thus represented on at least one branch of said tube thereat, said distance being sufliciently large to substantially prevent deleterious discharges at said junction, and a coat ,ing of light colored non-conductive material completing the reflector thus provided across the d scontinuity thus formed. i

4. A luminous tube in the formof a character to a branching. junction of said character and a reflective coating of conductive material disposed lengthwise along an outside surface of said tube,

[said tube being characterized by virtue of the presence of said coating by a tendency to electric breakdown at said section materially in excess of the breakdown tendency due to the proportionate voltage drop along said section with re spect to the voltage impressed across the extreme terminals of said tube, said coating being confined-to one of the opposing branches of said tube in said section to substantially prevent break- ,ontheoutside surface thereof and on the side' distantgfrom the normalposition of the observand having a section returning over its own course down tendency.

5. A luminous tube in the form of a character 1 down thereat because of said excessive breakand having a section returning over its own disposed lengthwise along'an outside surface of said tube, said tube being characterized by virtue of the presence of said coating by a tendency to electric breakdown at said section materially in excess of the breakdown tendency due to the proportionate voltage drop along said section with respect to the voltage impressed across the extreme terminals of said tube, said coating be- "ing confined to one of the opposing branches of said tube in said section and terminating a sumcient distance back from said junction on at least one of the branches of said tube from said junction to substantially compensate for: said excessive breakdown tendency. Y H p i 6. A luminous tube in theformjoi' a character having a section in the form of a loop of said character with spaced portions of said tube crossing each other at the junction 'of said loop and a reflective coating of conductive material disposed lengthwise along an outside surface of said tube, said tube being characterized by virtue of the presence of said coating by a tendency to electric breakdown at such approaching portions when continuously coated therealong materially in excess of the breakdown tendency due to the proportionate voltage drop along said section with respect to the voltage impressed across the extreme terminals of said tube, said coating terminating on at least one of said portions at said junction a suflicient distance from the other said portion of said tube at said junction to compensate for said excessive breakdown tendency.

7.;.A luminous tube in the form of a character having a section in the form of a loop of said character withspaced portions of said tube closely approaching each other'at the junction of said loop and a reflective coating of conductive material disposed lengthwise along an outside surface of said tube, said tube being characterized by virtue of the presence 01' said coatingby a tendency to electric breakdown at such junction it continuously coated thereat materially in tendencymaterially less thansaid excessive breakdown tendency if said coating beconflned to one of said portions of said tube at said junctiomsaid coating terminating on one of said portions at said junction a suflicient distance from the other Portion of said tube at said junction to limit the breakdown tendency to a value materially less than said excessive value. p

8. A luminous tube'provided with areflective coating of conductive material disposed lengthwise along an-outside surface thereof and having a configuration in its outline, said tube being characterized by a materially greater tendency to electric breakdown at said configuration if said coating is continuous thereat than if some oiv said coating is removed from thesurface of saidtube thereat, said" excessive break down tendency being materially greater than the proportionate breakdown tendency with respect to the voltage impressed across the extreme terminals of said tube. said tube being selectively coated at said configuration to reduce said breakdown tendency thereaccording. V v

9. A luminous tube provided with a'reflective coating of conductive material disposed lengthwise along an outside surface thereof and having a configuration in its outline, said tube being characterized by a tendency to electric breakdown .at said configuration greatly in excess of the proportionate voltage drop thereat with respect to the voltage impressed across the terminals of said tube'in normal operation thereof, and

means to prevent electric breakdown at said 0on figuration.

ARTHUR CLIFTON DEANS. 

